Commercial grades

Commercial-grade zirconium contains from 1 to 3% hafnium. Zirconium has a low absorption cross section for neutrons, and is therefore used for nuclear energy applications, such as for... 

Cerium is a component of misch metal, which is extensively used in the manufacture of pyrophoric alloys for cigarette lighters. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. The oxide is an important constituent of incandescent gas mantles and is emerging as a hydrocarbon catalyst in self cleaning ovens. In this application it can be incorporated into oven walls to prevent the collection of cooking residues. 

Carbon disulfide, CS2 commercial grade which is colorless. 

In normal practice, inhibitors such as hydroquinone (HQ) [123-31 -9] or the monomethyl ether of hydroquinone (MEHQ) [150-76-5] are added to acrylic monomers to stabilize them during shipment and storage. Uninhibited acrylic monomers should be used prompdy or stored at 10°C or below for no longer than a few weeks. Improperly iahibited monomers have the potential for violent polymerizations. HQ and MEHQ require the presence of oxygen to be effective inhibitors therefore, these monomers should be stored in contact with air and not under inert atmosphere. Because of the low concentration of inhibitors present in most commercial grades of acrylic monomers (generally less than 100 ppm), removal before use is not normally required. However, procedures for removal of inhibitors are available (67). 

Raw Material. The principal raw material for fluorine production is high purity anhydrous hydrofluoric acid. Each kilogram of fluorine generated requires ca 1.1 kg HE. Only a small portion of the hydrofluoric acid produced ia the United States is consumed ia fluorine production. The commercial grade is acceptable for use as received, provided water content is less than 0.02%. Typical specifications for hydrofluoric acid are... 

Bromine Trifluoride. Bromine trifluoride is a colorless Hquid. The commercial grade is usually amber to red because of slight bromine contamination. The molecule has a distorted T stmeture (26). Infrared spectral data (26—30), the uv-absorption spectmm (31), and vapor pressure data (32) may be found in the Hterature. 

Economic Aspects. Halocarbon Products Corp. is the largest producer of trifluoroacetic acid. The commercial grade is of very high purity with the main impurity being ca 0.2% water. A grade, which has a low residue specification, intended for use in protein synthesis (Biograde) is available. Other producers include Rhc ne-Poulenc and Solvay. The 1992 price was ca 15/kg. 

Two-Step Process. The significant advantage of the two-step process is that it only requkes commercial-grade methyl formate and ammonia. Thus the cmde product leaving the reactor comprises, in addition to excess starting materials, only low boiling substances, which are easily separated off by distillation. The formamide obtained is of sufficient purity to meet all quaUty requkements without recourse to the costiy overhead distillation that is necessary after the dkect synthesis from carbon monoxide and ammonia. 

Table 1. Density and Concentration of Commercial Grades of Hydrochloric Acid...

The cmde product from any hydrogen peroxide process can be used as such, but commercial grades are further purified, concentrated, and stabili2ed. 

The analysis of partially dried lead concentrate, ready to be treated in a series of processes to produce a commercial grade of lead, is presented in Table 2. 

In general, LPG specifications involve limits for physical properties. Consequentiy, the composition of the commercial-grade products varies between wide limits. Physical properties of the principal components of LPG are summarized in Table 1 (1). 

Manufacture and Processing. Most commercial-grade magnesium hydroxide is obtained from seawater or brine using lime or dolomitic... 

Table 13. Properties of Commercial-Grade Magnesium Hydroxide Powders...

The detrimental effects of Si addition are (/) Si iacreases the yield strength and decreases the ductiHty of iron such that commercial-grade materials are limited to ca 4% Si, and (2) as shown ia Eigure 3, the saturation iaduction and Curie temperature are decreased with increasing siHcon content. 

Acute oral LD q data for nitro alcohols in mice are given in Table 1. Because of their low volatiHty, the nitro alcohols present no vapor inhalation ha2ard. They are nonirritating to the skin and, except for 2-nitro-1-butanol, are nonirritating when introduced as a 1 wt % aqueous solution in the eye of a rabbit. When 0.1 mL of 1 wt % commercial-grade 2-nitro-1-butanol in water is introduced into the eyes of rabbits, severe and permanent corneal scarring results. This anomalous behavior may be caused by the presence of a nitro-olefin impurity in the unpurifted commercial product. 

Table 6. Typical Properties of Commercial-Grade Nitroparaffins...

Commercial-grade nitroparaftins are shipped and stored ia ordinary carbon steel. However, wet nitroparaftins containing more than 0.1—0.2% water may become discolored when stored ia steel for long periods, even though corrosion is not excessive. Aluminum and stainless steel are completely resistant to corrosion by wet nitroparaftins. Storage ia contact with lead (qv), copper, or alloys containing these metals should be avoided. Polymeric materials for gaskets, hoses, and connections should be tested for thek suitabiHty before exposure to nitroparaftins. 

Additives and Modifications. For plastics uses, nylon is only rarely employed as the pure polymer, and is almost always modified to some extent even if only with the addition of a small amount of lubricant. There has been a dramatic increase in the range and number of combinations of additives used to modify nylons, resulting in a huge expansion in the number of commercial grades available and the uses to which they can be put. It is not unusual to find formulations that contain less than 50% nylon and half a do2en or more additives. 

---